Manufacture of lubricating oils



Patented Sept. 23, 1930 UNITED STATES PATENT orrlca GESELLSCHAFT, M. H., OF BERLIN, GERMANY MANUFACTURE OI LUBBICATING OILS No Drawing. Application filed May 28, 1928, Serial No. 281,369, and in Great Britain April 14, 1928.

The present invention pertains to the manufacture of lubricating oils, and aims to produce lubricating oils of superior properties from mineral oils.

" More particularly, it relates to the treatment of lubricating oil stock after removing the lighter fractions, and consists in subjecting appropriate mineral oil fractions to the Well known extractiontreatment with liquefied sulfur dioxide to remove constituf ents soluble therein, for exam le, unsatu-. rated aromatic hydrocarbons, followed by distillation of the insoluble constituents in the presence of a little alkali, with or with out reduced pressure, and with or without the presence of water vapor.

The distillation products thus obtained are distinguished from those heretofore produced by complete freedom from acid, by

eating 0115 which comprises treating with reduced content of tar, by stability of color, and by increased resistance to oxidation.

In particular (a) all of the fractions obtained when distilling previously extracted lubricating oil stock in the presence of'causv tic soda are completely free from acid; (b) the tar content is on the average 2% less than with the same extracted stock not distilled in the presence of caustic soda or alkali. a

By way of example, the process may be operated as follows: 1 v.

The residual material obtained after ex tracting the lubricating oil stock with liquefied sulfur dioxide at a' temperature between 10 C. and +30 'C. is mixed with a concentrated aqueous solution of caustic soda amounting to 1% of NaOH in respect of the oil treated, and the mixture is thoroughly agitated prior to being distilled. The distillation proceeds preferably in the known manner according to the vacuum process, with a pressure of 7-15 mm. mercury, and with or without passing a current of steam throughthe stillfitHighly satisfactory results have thus been obtained? The process is not restricted to the specific materials and exactv operations described, but may be applied to the production of lubricating oils generally from .available petroleum stocks, particularly in the Texas and California fields.

I claim the following as my. invention:.

1. In the manufacture. of lubricating oil from mineral oil stock, extracting the stock with liquefied sulphur dioxide at low temperatures toseparate the, desirable lubricating stock from the soluble undesirable constituents and distilling the insoluble lubricatin stock in the presence of an alkali.

2. n the manufacture of lubricating oil from mineral oil stock, extracting the stock with liquefied sulphur dioxide at low temperatures to separate the desirable lubricating stock from the soluble undesirable constituents and distilling'the insoluble lubrieating stock under a Vacuum in the presence of an alkali.

3. The step in the manufacture of lubrilique d sulfur dioxide petroleum lubricatoil stock obtained by fractional distillation, and subjecting the portion insoluble in-liquefied sulfurous acid to distillation in the presence of a concentrated aqueous solution of caustic soda amounting to 1% NaOH with respect to the oil being treated.

4. The step in the manufacture of 1ubrieating oils which comprises treating with lique ed sulfur dioxide petroleum lubricating oil stock obtained by fractional distillation, and subjecting the portion insoluble in liquefied sulfurous acid to vacuum distillation under a pressure of 7-15 mm. mercury in the presence ofa concentrated aqueous solution of caustic soda.

5. An acid free lubricating oil low in tar obtained by the treatment of suitable min-- eral oil fractions'with liquefied sulfur dioxide to dissolve unsaturated hydrocarbons and separation of the latter to remove the constituents soluble thereimfollowed by distillation of the insoluble constituents in the presence of an alkali.

. 6. A substantially acid-free lubricating oil of low viscosity and tar content obtained by the extraction of suitable natural mineral oil fractionswith liquefied sulfur dioxide to dissolve unsaturated hydrocarbons and sepa-.

ration of the latter to remove the constituents 2 r mam soluble therein, followed by vacuum distillation of the insoluble constituents in the presence of an alkali.

7. A substantially acid-free lubricating oil of low viscosity and tar content obtained by the extraction of suitable natural mineral oil fractions with liquefied sulfur dioxide to dissolve unsaturated hydrocarbons and separation of the latter to remove the constituents soluble therein, followed by distillation of the insoluble constituents in the presence of an alkali and steam.

In testimony whereoflI have signed my name to this specification.

' LAZAR EDELEANU. 

